A conventional switch device, especially for those switches using a bimetallic plate to prevent from being burned when an overload occurs, generally includes a bi-metallic plate which is deformed when overloaded so as to separate the two contact points respectively located on the bi-metallic plate and one of the two terminals. U.S. Pat. Nos. 5,262,748; 4,167,720; 4,937,548; 5,223,813; 5,451,729; and 5,558,211 disclose related switch devices. Some inherent shortcomings for these conventional safety switch devices are found. There are too many parts involved in the safety switch device and a longer period of time is required when assembling the switch device, this increases the cost of the products. The parts might be arranged inaccurately and affect the deformation of the bi-metallic plate. Once the bi-metallic plate is deformed to cut off the circuit, because of the improper arrangement of the parts as mentioned above, the bi-metallic plate could deform to re-connect the two contact points to connect the circuit again. Because the inaccuracy of the deformation of the bi-metallic plate, the switch member does not set the “OFF” position after the bi-metallic plate is deformed to cut off the circuit.
Therefore, it is desired to have a safety switch that allows the bi-metallic plate to deform toward a desired direction and also have enough space to prevent the bi-metallic plate from bouncing back to connect the circuit again.